Method for rectifying petroleum oils



May 3, 1932. P. c. KEITH. JR

METHOD FOR RECTIFYING PETROLEUM OILS Filed July 10, 1928 3 5 Oky OOOOMOOO Patented May 3, 1932 UNITED STATES PATENT OFFICE PERCY G. KEITH, 33., O1 BEBNABDSVILLE, NEW JERSEY, ASSIGNOR TO THE M. W. KELLOGG COMPANY, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE METHOD FOR nncrirxmo PETROLEUM oILs Application filed JuIy IO, 1928. Serial No. 291,609.

This invention relates to a method for stripping cuts of petroleum oil from a rectifying column operated under vacuum and will be understood from the following description read in conjunction with the draw 1% ings, in which:

Fig.' 1 is a vertical elevation of parts in section of a preferred form of apparatus; and Fig. 2 is a detail vertical section of part of Fig. 1. 1 w Referring specifically to Fig. 1, oil may be supplied through pipe 1 controlled by valve 2 to the tubular heater 3. This consists of a series of tubes joined end to end by crossover connections to form a continuous circuit and will be hereinafter referred to as a'pipe still. The pipe still 3 is surrounded by refractory setting 4 which may be heated through the port 5 by the burner 6. The pipe still discharges through the outlet 56 and distributor 6d into the drum 7. The outlet 55 is surrounded by thermal insulation 5a and the drum 7 by thermal insulation 70:. Horizontal partitions 8 and 9 respectively are located in'the drum 7 below and above the distributor 6a. These partitions are preferably equipped with vapor distributors such asbell-caps and overflow pipes of the conventional type to contact liquids and vapors. The pipe 60; controlled by the valve 62') discharges steam through the distributor 60 into the drum preferably below the partition 8. The pipe 10 projects upwardly into the drum 7 from the lower part thereof permitting the accumulation of liquids in the drum up to the level of the topof the pipe 10. Any excess may be withdrawn through the pipe 10 by manipulation of the valve 11. Vapors evolved in the drum pass off through the pipe 12 surrounded by thermal insulation 12a into the rectifying column 13. This column is preferably surrounded by asuitable thermal insulation, not shown. The column 13 carries a number of transverse partitions 13a which are preferably equipped with liquid vapor contacting devices, such as bellcaps and overflow pipes, to divert an excess of liquid from an partition to that immediately beneath. ottoms accumulating in the W base of the column 13 may be continuously or ltti periodically withdrawn throughthe pipe 14 controlled by the valve 15. Cooling coils 16 and 17 are provided in the upper part. of the column. Water may be supplied to the coil 16 through the pipe 18, and oil is supplied through the pipe 19 to the coil 17. This oil will in operation be pre-h'eated in the coil 17 and thereafter discharged through pipe 1 into the pipe still 3. Draw-off pipes 20, 21, 22, 23 and 24 are connected into the column at intervals to draw off liquor from the horizontal partitions 13a. These pipes are connected through traps 25, 26, 27, 28 and 29 into a number of auxiliary rectifying columns '30, 31, 32, 33 and 34. The amount of liquor diverted into these columns may be controlled by the valves 35, 36, 37, 38, and 39 respectively. A common pipe 40 leads upwardly alongside of the column and connects into the upper part of the column at the point 41. Steam may be admitted to the auxiliary column 34 by means of the pipe 42 controlled by the valve 43. Steam may be admitted to the auxiliary column 33 by means of the pipe 44 controlled by the valve 45. Steam may be admitted to the auxiliary column 32 by means of the pipe 46 controlled by the valve 47. Steam ma be admitted to the rectifying column 311iiy means ofythe pipe 48 controlled by the valve 49. Steam may be admitted to the rectifying column 30 by means of the pipe. 50 controlled by the valve 51. Vapors passing upwardly from the auxiliary column 34 are diverted by means of the pipe 52 controlled by the valve 53 into the pipe 35 40. Vapors passing upwardly from the auxiliary column 33 are diverted by means of the pipe 54 controlled by the valve 55 into the common pipe 40. Vapors passing upwardly from the auxiliary column 32 are diverted by means of the pipe 56 controlled by the valve 57 into the common pipe l0. Vapors passing upwardly from the auxiliary column 31 are diverted by means of the pipe 58 controlled by the valve 59 into the common pipe '40. Vapors passing upwardly from the auxiliary column 30 are diverted by the pipe 60 controlled by the valve 61 into the common pipe 40.

Fig. 2 shows in detail the construction of W the rectifying column and auxiliary columns. Each auxiliary column carries two partitions such as 62 and 63 located respectively above and below the inlet, which partitions carry vapor distributors 64 and 65 and overflow pipes 66 and 67. The steam pipe 48 terminates in the I distributor 49.

Referring again to Fig. 1 vapors may be conducted away from the upper part of the denser 75 which discharges through the pipe 70 discharging into the jet ejector 71 which is supplied with super-heated steam by means of the pipe 72 controlled by the valve 73. The outlet end of the jet ejector is connected through the pipe 74 to the barometric condensor 75 which discharges through the pipe 76 and receives condensing water through the pipe 77 controlled by the valve 78. Cuts from the fractionating column 13, which have been stripped in the respective auxiliary columns, may be withdrawn to storage by means of the pipes 7 9, 80,81, 82 and 83.

The method of operation of the apparatus is substantially as follows: 7

A petroleum oil to be fractionated is supplied through the pipe 19, coil 17 and pi e 1 to the pipe still 3, wherein it is heated y means of the burner 6 to a temperature of complete or partial vaporization.. Any petroleum oil may be employed for this purpose although preferably operate with a pctroleum oil containing lubricating compo nents, such as a residuum of crude oil, viz., one from which gasoline, kerosene and gas oil have been removed. The vaporized or part- 1y vaporized oil is discharged into the drum 7 by means of thedistributor 6d. Steam for stripping is introduced by means of the pipe 6a controlled by the valve 61) terminating inthe distributor 6a. This steam strips the lighter components from the unvaporized liquid residuum and passes upwardly together with the hydrocarbon vapors to be conducted through the pi e 12 into the rectifying column 13. Recti cation takes place in 13 and is preferabl maintained under conditions of substantially complete condensation of the hydrocarbons at the top of the rectifying co umn. For this purpose the amount of cooling medium supplied to the coils 16 and 17 is so controlled as to produce substantially complete condensation of the hydrocarbons reaching the upper part of'the tower, while permitting substantially all of the steam to pass overhead and escape from the column through the pipe 70. The operation is preferably conducted under vacuum and the jet ejector 71 and barometric condenser are simultaneously operated for this purpose. The jet ejector preferably maintains a vacuum in the upper part of the tower corresponding to an absolute pressure of less than 50 mm. and apressure of 7 5 to 150 mm.

at the outlet end. This pressure of 75 to 150 mm. is taken care of by the operation of the barometric condenser 75. A liquid residuum of heavy lubricatin oil collects in the base of the tower 13 an is withdrawn either continuously or at intervals through the pipe 14 to storage. Individual lubricating cuts are tapped off from the column by means of the pipes 20, 21, 22, 23 and 24 and discharged by manipulation of the valves 36, 37, 38 and 39 into the respective auxiliary columns 30, 31, 32, 33 and 34. Inasmuch as these auxiliary columns are connected through the pipe 40 to the top of the column, the absolute pressure in the auxiliary columns is less than that obtaining within the primary column 13 at the respective points of withdrawal. It will of course be understood that there is a drop in pressure in each upwardly succeeding plate of the primar column due to resistance to flow and other actors and that the pipe 40 being connected into the top of the primary column will be at a lower absolute pressure than that obtaining in the column at the location of the pipes 20, 21, 22, 23 and 24. This diminished pressure automatically results in a very substantial stripping of the individual cuts discharged into the auxiliary columns and this is further enhanced by the admission of small quantities of steam to these respective columns by means of the pipes 42, 44,46, 48 and 50 respectively. The cuts after strlppingin the auxiliary columns are withdrawn to storage through the pipes 79, 80, 81, 82 and 83 respectively.

It will of course be understood that the foregoing specific description of method and apparatus is by way of illustration and not of limitation. It is my intention that the invention be limited only by the appended claims, or their equivalents, in which I have epdeavored to claim broadly all inherent nove ty.

I claim: 1

1. In the fractionation of petroleum oil in a rectifying column operating under vacuum having a plurality of rectifying zones under low absolute pressures in communication, the method of stripping fractional condensates withdrawn from a plurality of said zones which comprises discharging such'fractional condensates separately into auxiliary rectifying zones in free and unrestricted communication with the upper part of said rectifying column.

2. In the fractionation of petroleum oil in a rectifying column operating under vacuum having aplurality of'rectifying zones under progressively varying lowabsolute pressures in communication with each other, the method of stripping fractional condensates in said zones which comprises withdrawing fractional condensates from the several zones, and discharging such fractional condensates separately into auxiliary rectifying zones in free and unrestricted communi- Slit) cation with said rectifying column at a point alcove the zones from which the fractional condensates have been withdrawn.

3. tn the fractionation of petroleum oil under vacuum, the method of fractionation in a plurality of rectifying zones in communication under progressively varying low absolute pressures, which comprises withdrawing fractional condensates from some of said zones, and discharging said fractional condensates separately into auxiliary rectifying zones in free and unrestricted communication with one of the first mentioned rectifying zones under lower absolute pressure than the zones from which the fractional condensates have heen withdrawn.

4. In the fractionation of petroleum oil under vacuum, the method of fractionation in a column of rectifying zones in communi cation with each other under low absolute pressures progressively decreasing toward one end, which comprises withdrawing frac- 'tional condensates from zones intermediate the ends of the column, and discharging said fractional condensates separately into auxiliary rectifying zones the upper portions of which are in free and unrestricted communi cation with one of the first mentioned rectifying zones under lower absolute pressure than the zones from which the fractional condensates were withdrawn whereby the fractional condensates are stripped of light components.

5. In the fractionation of petroleum oils under vacuum, the method of fractionation in a vertical column of recti zones in communication with each other under low absolute pressures progressively decreasing towards the top of the column, which comprises withdrawing fractional condensates from a plurality of the zones below the top of the column, discharging the withdrawn fractional condensates separately into a plurality of auxiliary rectifying zones, stripping the fractional condensates in the auxlliary rectifying zones with steam, passing the steam and the light oil vapors from all of the auxiliary rectifying zones through a common conduit into the top of the column, and

separately withdrawing the stripped frac-' tional condensates from the several auxiliary rectifying zones.

fn testimony whereof, I have signed my name to this specification this 5th day of 55 July, 1928.

PERCY C. KEITH, JR. 

